This invention relates generally to the field of scaffolds and pertains more particularly to headers for scaffolds used for supporting planks.
The uses of scaffolding are manifold and thus a prime requirement for a scaffolding system is adaptability to the various tasks. Scaffolds may be used for providing walkways and support for workmen constructing buildings, painting, cleaning, welding, etc. It naturally is important that scaffolds be secure and sturdy so that bystanders and workmen using the scaffolds are protected.
Prior art scaffolds have included scaffold end frames connected by cross braces to form a three dimensional rectangular unit. Typically, a plurality of frames may be interconnected vertically and horizontally to form extensive structures adapted to the particular task at hand.
Scaffolds typically include planks of wooden lumber laid side-by-side and supported on opposite ends by the end frames to provide an elevated walkway. Hooks have sometimes been fixed in the ends of these wooden planks to clip over horizontal braces on the end frames to prevent the planks from disengagement from the end frames.
Usually, however, the planks have simply been made longer than the space between the end frames so that the opposite ends of the planks extend beyond the frames. As a result, adjacent ends of the planks overlie one another at the end frames resulting in an uneven walkway surface. Another disadvantage of such a walkway is that movement of one plank, caused, for example, by simply walking or moving equipment on the plank, may result in movement and vibrations in other planks up and down the row. Also such prior art planks may be accidentally kicked out by a workman or may drop out if the scaffolding moves or expands when stress is applied to it.
These and other disadvantages of the conventional prior art scaffolds have led to the invention of scaffold assemblies employing rectangular, folded hollow metal planks. These scaffold assemblies have typically supported adjacent plank ends on a shelf-like horizontal member integral with the end frames. Such prior art scaffold configurations provide a flat, even walkway but have had the disadvantage of requiring extensive cross-bracing to prevent relative horizontal movement of the end frames so as to insure that the end frames never inadvertently spread far enough apart in the horizontal direction so as to allow the metal planks to become dislodged from the shelf-like horizontal member and fall through.
Prior art scaffold systems have also sometimes included side brackets which are cantilevered from the types of scaffolds and end frames described above. Such side brackets may be used to support planks in the same ways described above.